Multiple Unit Large Volume in situ Filtration System Protocol
James K.B. Bishop
Many of the procedural details for sample handling, sample splitting,
blank control, etc. are published. See Bishop et al. (1985) for a
description of sample processing schemes.
Cast documentation Casts will be identified by standard operation
number, date, time of start of cast, filtration starting (time, lat.,
long.), filtration ending (time. lat., long.), and time of end of cast.
Samples in each cast will be identified by nominal wire out depth, pump
number, filter holder number, and volume of water filtered.
Depth history of samples determined by real time telemetry of
pressure at two sampling locations as well as by internally recording
Applied Microsystems STD located at deepest part of the cast.
Pump handling Where practical, pumps will be covered with plastic
between stations; they will be rinsed with fresh water immediately prior
to and after each cast.
Filter holder handling Filter holders and components will be detergent
cleaned and acid leached prior to each cruise. They will be rinsed with
Milli Q water after each use. They will be covered with plastic at all
times until just prior to immersion in the ocean. Plastic covers will be
replaced immediately upon recovery.
Sample handling All MULVFS samples will be processed in a laminar flow
clean bench aboard ship. Non- contaminating gloves, subsample templates,
and tweezers will be used.
Once subsampling is complete the samples are oven dried at 60-70
degrees C for 1-2 days. This procedure is described by Bishop et al.
(1985). They are stored dry in clean polyethylene bags.
Filter types We use a series of standard filter types in each sample:
53 um Polyester screen, and 2 identical Whatman QM/A quartz fiber filters
(pore size is approximately 1 um). The Polyester screened sample is
operationally defined as the >53 um fraction, the two QM/A filters are
defined as the 1Ż53 and <1 um fractions, respectively. The latter
designation is not quantitative since only a fraction of submicron
material is retained by the filter. We will endeavor to compare our
estimates of particulate organic matter using these filters with that from
Whatman GF/F glass fiber filters, which are frequently used for
particulate carbon work. Whatman GF/F's are precluded for our work
because they have high and variable major ion and trace metal blanks.
Additional efforts to better characterize the submicron organic fraction
are in development stages at this time.
Blanks Filter blanks are determined using unused and process blank
filters A process blank filter is one which is deployed at depth on a
pump but has no water pumped through it. This filter is processed in an
identical way to samples. Process blanks will be obtained at least once
every other station. One unused filter set will be retained for blank
purposes at least once every 30 samples.
Large particle density and size distributions >53 um particle size
distributions are determined by optical color (8 bit RGB) scanner.
Samples within polyethylene bags are imaged at 300 dpi (dots/inch; 1 dpi
is approximately 70 um). Scanner is calibrated with a known photographic
gray optical density standard. This method quantifies mass loading of 53
um Polyester filters which allows subsampling at sea.
Microscopy Selected samples will be analyzed by light microscopy and SEM
when chemical data indicate important features in the particle field or
when major issues need to be resolved regarding estimates of particle
Dry weight This procedure is discussed in Bishop and Edmond .(1976).
Typical quantities of particulate matter obtained in each MULVFS sample
are 100-200 mg (1-53 um fraction) and 10's to 100 mg (>53 um fraction).
53 um Polyester, and 1 um microquartz filters are preweighed to better
than 1 mg. Unused reference filters are used to track variations in room
humidity during weighing. These control filters also track variations in
dry weight due to humidity differences between the time the filters were
originally weighed and after the samples are obtained. A humidity
controlled and particle-free environment is used for this work. Samples
must be rinsed to reduce the sea salt content ten-fold in order to get
decent dry weights. This results in potential loss of organics and labile
elements. (This effect is no more than 15% for bulk carbon, Bishop and
Edmond, 1976). UNRINSED SUBSAMPLES MAY BE OBTAINED. The contribution of
sea salt to dry weight values are corrected for by analyzing Na. Of the
major ions (Na, Mg, K and Ca), Na is discriminated against by organisms
and therefore is the best estimator of sea salt.
C, N, S Samples are fumed with 12N HCl ( to remove carbonates) in closed
container overnight. Carlo Erba elemental analyzer: standards and
analyzer blanks by usual procedures. One in every ten samples is
repeated, a reference sample is run one each run of 50 samples and
standards. >53 um organic matter is estimated gravimetrically by
subtracting inorganic species from dry weight. Nitrogen cannot be
estimated on nitex samples without mechanical removal of material from the
filter. Sea salt sulfur is determined by Na analysis.
Na, Ca, Mg, K 0.6N HCl leach, at 60 degrees C overnight, followed by
separation (Nuclepore filtration) of leachate and remnant filter material.
Analysis by flame atomic absorption (or plasma emission). Procedures are
standard. Quality control for major ion analysis is the parallel analysis
of a sea water sample of known salinity as well as through 1:10 repeat
analysis of samples and reference sample. Na, Mg, K, and Ca are
conservative in seawater to better than 1%. Methodology is described in
Bishop et al. (1977).
Sr Determined on major ion leach solutions either by flame AA, ICP-MS,
or GFAAS. Methodology is described in Bishop et al. (1977).
Calcium carbonate At least 90% of Ca (in excess of sea salt) is calcium
carbonate (Bishop et al., 1977). We plan to use coulometric analyzers to
determine inorganic carbon directly in several profiles to better
calibrate this percentage.
P Phosphorus is released from particles to solution by a three step
persulphate oxidation process and analyzed colorimetrically. Methodology
is described in Bishop et al. (1977), but may be improved. QC as for
Si (opal) 53 um nitex samples are leached in 1M NaCO overnight. After
filtration, samples are neutralized with HCl and analyzed using the
standard nutrient method (Bishop et al., 1977). 1-53 um opal is hard to
do on quartz fiber filters, but has been estimated gravimetrically (Bishop
et al., 1977). We will try to estimate opal by germanium analysis (Ge:Si
in opal is constant; Ge is probably not a contaminant of microquartz
filters). Methodology will be developed for the ICP-MS. Failing this we
plan to collect 0.4 um Nuclepore filter samples using the parallel
sampling capabilities of MULVFS. These filters would be leached and
analyzed as above.
Al Total digest of sample followed by ICP-MS of AlO+, or GFAAS. L-DEO
presently has established methodology for sediment and sediment trap
analysis. We will adapt these techniques to water column particulate
matter samples. QC as for other elements.
Ba Major ion leach solutions are analyzed by GFAAS method of Bishop
(1990) or by ICP-MS. Results are representative of total barium sulfate
(the dominant phase) and absorbed/ion-exchangeable barium. QC is the same
as for major ions. Blanks are controlled by analysis of unused and
procedural blanks as well as through analysis of paired quartz filter (>1
vs. 1-53 um size fraction).
Reactive Mn Archived major ion leach solutions are analyzed by GFAAS
method of Bishop and Fleisher (1987) or by ICP-MS. All `reactive∆ Mn is
quantified by this method. QC is the same as for major ions.
Leachable Fe, Cu Analysis scheme similar to that for Mn by GFAAS. We
will develop and test methodology ensure complete recovery of leachable
Pb Analysis by GFAAS (platform) or by ICP-MS. GFAAS methodology is
standard. QC is identical to that for Ba, Mn, Cu.
- Bishop, J.K.B. and Edmond, J.M. (1976).
- A new large volume filtration
system for the sampling of oceanic particulate matter. Journal of Marine
Research, 34: 181-198.
- Bishop, J.K.P., Edmond, J.M., Ketten, D.R., Bacon, M.P., and Silker, W.B.
- The chemistry, biology and vertical flux of particulate matter
from the upper 400 m of the equatorial Atlantic Ocean. Deep-Sea Research,
- Bishop, J.K.B., Schupack, D., Sherrell, R.M., and Conte, M.
- A Multiple Unit Large Volume in-situ Filtration System (MULVFS)
for sampling oceanic particulate matter in mesoscale environments. pp.
155-175 In: A. Zirino (ed.), Mapping Strategies in Chemical Oceanography,
Advanced in Chemistry Series, Vol. 209, American Chemical Society,
- Bishop, J.K.B. (1986).
- The correction and suspended mass
calibration of Sea Tech transmissometer data. Deep-Sea Research, 33:
- Bishop, J.K.B. and Fleisher, M.Q. (1987).
- Particulate manganese
dynamics in Gulf Stream warm-core rings and surrounding waters of the N.W.
Atlantic. Geochimica et Cosmochimica Acta, 51(10): 2807-2826.
- Bishop, J.K.B. (1990).
- Determination of Barium in seawater using
vanadium/silicon modifier and direct injection graphite furnace atomic
absorption spectrometry. Analytical Chemistry, 62: 553-557.